> If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.

> build upon the material

Is there clearly defined difference between "build upon the material" and "using the material as part of your project"? Commercial use in most cases involves not wanting to release your own project under CC BY-SA 4.0. Even though it's possible to combine both (commercial use and CC BY-SA 4.0 for your own product), it's highly unlikely.